1. Field of the Invention
The present invention generally relates to an adjusting method, and more particularly to an adjusting method of a gamma voltage adjusting device.
2. Description of Prior Art
In a liquid crystal display device, there are two methods for adjusting gamma voltages. A first method is to adjust the gamma voltages by hardware. A second method is to adjust the gamma voltages by software, such as a timing controller (T-con) for adjusting data. Please refer to FIG. 1 and FIG. 2. FIG. 1 illustrates a method for adjusting the gamma voltages by hardware in the prior arts. FIG. 2 illustrates relationships of the gamma voltages and transmittances in the prior arts. Taking 256 gray levels for example, a printed circuit board assembly (PCBA) 10 firstly generates 2N gamma voltages, which comprises N negative polarity gamma voltages GMA1-GMAN and N positive polarity gamma voltages GMAN+1-GMA2N. The N negative polarity gamma voltages GMA1-GMAN and the N positive polarity gamma voltages GMAN+1-GMA2N are inputted to a data chip 12. The data chip 12 generates 256 negative polarity driving voltages V255-V0 according to the N negative polarity gamma voltages GMA1-GMAN and generates 256 positive polarity driving voltages V0′-V255′ according to the N positive polarity gamma voltages GMAN+1-GMA2N. The negative polarity driving voltages V255-V0 and the positive polarity driving voltages V0′-V255′ are utilized for driving pixels to display one of the 256 gray levels.
It can be understood from FIG. 2 that the N negative polarity gamma voltages GMA1-GMAN and the N positive polarity gamma voltages GMAN+1-GMA2N are generated in pair. That is, each of the gray levels is controlled by two gamma voltages (a negative polarity gamma voltage and a positive polarity gamma voltage), so as to adjust the gray levels to be close to a gamma curve and ensure that the N negative polarity gamma voltages GMA1-GMAN and the N positive polarity gamma voltages GMAN+1-GMA2N in FIG. 2 are symmetrical with respect to a common voltage VCOM. The gray levels can be adjusted to be close to the gamma curve by adjusting the data chip 12. The N negative polarity gamma voltages GMA1-GMAN and the N positive polarity gamma voltages GMAN+1-GMA2N need to be symmetrical with respect to the common voltage VCOM by utilizing the printed circuit board assembly 10 to generate the 2N gamma voltages. Since the 2N gamma voltages of the printed circuit board assembly 10 are generated by gamma integrated circuits (gamma ICs), a number of the required gamma integrated circuits is a burden of cost.
Consequently, there is a need to solve the problem that the cost cannot be reduced because the number of the gamma integrated circuits cannot be decreased in the prior arts.